In the field of semi-automatic firearms it is well known to provide a tube-type magazine which holds in vertical relationship a series of rounds of ammunition and feeds them successively upwardly to the chamber of the gun. In loading the gun, the magazine or clip is inserted upwardly into a downwardly opening chamber in the handgrip of the gun by an upward force applied to the bottom wall or butt plate of the clip. This force is typically exerted by the palm of the user's hand. The butt plate of the magazine is in many instances mounted slidably to the lower end of the tubular body for horizontal detachment therefrom for ease of assembly and disassembly for servicing, etc. A drawback associated with such slidable butt plates is that the force exerted by the user's palm during repeated insertions into the gun tends to slide the butt plate off the tubular body of the magazine.
In order to prevent such sliding, magazines have been provided with floor or latch plates which, as disclosed in U.S. Pat. No. 4,397,109, are disposed within the bottom of the magazine in engagement with the lower end of the magazine spring. Such plates include a projection or lug to releasably engage an opening provided through the butt plate to releasably retain the butt plate in fixed relation on the bottom of the magazine. A drawback to this approach is that the latch plate has a tendency to move upwardly or "submarine" into the magazine with the application of a relatively large force to the butt plate in it's "off" direction whereby the butt plate is then free to slide off the magazine tube or box. Such so called "submarining" will generally occur when the latch plate is being pushed forward by movement of the butt plate toward the forward wall of the magazine where it works its way upward alongside the spring. The result is that the butt plate is no longer latched in place by the floor or latch and is free to move relative the magazine.
Other mechanisms devised to secure slidable magazine butt plates to magazine tubes or boxes also have undesirable characteristics. For instance, the butt plate disclosed in U.S. Pat. No. 4,107,862 is slidably removable from the tube by compressing flexible side walls of the tube to allow tabs disposed thereon to clear retention lips of the butt plate. The requirement of flexible walls in such a configuration would provide a magazine having an inherent lack of structural integrity which could lead to the undesirable result of failure of the magazine in the field.
It is an object of this invention to provide an improved magazine for a semiautomatic handgun.
It is another object of this invention to provide a magazine assembly including a non-submarining floor or latch plate having means to releasably prevent sliding movement of a butt plate.
It is a further object of this invention to provide a magazine having a latch and butt plate assembly which overcomes the drawbacks of magazine butt plate devices heretofore available.
A further object of this invention is to provide a magazine assembly that is lightweight and relatively inexpensive to manufacture while being reliable in operation.
Another object of this invention is to provide a magazine assembly which is easier to assemble than prior art devices while providing a high degree of structural integrity.
Yet a further object of this invention is to provide a simple and effective magazine and butt plate construction so that different length magazine tubes can be accommodated in the same gun without the likelihood the wrong butt plate being improperly used on the wrong size magazine.
According to this invention, a magazine has a lower end closure that includes a floor plate disposed within the lower end of the magazine and includes a lug which interengages with an opening in a butt plate. A tongue is provided on the leading edge of the closure which is adapted to interengage with a notch in the lower edge of the magazine. This arrangement serves to retain the leading edge of the closure plate in place within the magazine tube while permitting the closure plate to be pivoted sufficiently against the bias of the magazine spring when the lug to be depressed to clear the opening of the butt plate for the installation and removal of the butt plate.
The above and other objects and advantages of this invention will be more readily apparent from a reading of the following description of an exemplary embodiment thereof taken in conjunction with the following drawing.